- From: Hugo Haas <hugo@w3.org>
- Date: Wed, 24 Jan 2001 10:33:37 -0500
- To: Mark Nottingham <mnot@akamai.com>
- Cc: Henrik Frystyk Nielsen <frystyk@microsoft.com>, "Eric Prud'hommeaux" <eric@w3.org>, xml-dist-app@w3.org
On Tue, Jan 23, 2001, Mark Nottingham wrote: > I also see some reference to footers here, which makes me scratch my > head a bit. I can see two possible reasons why this would be > desireable; > > * To "stream" messages, much as chunking and Trailers do in HTTP. My > understanding was that XP messages were to be considered and > processed only as a whole; processing messages before they are > complete leads to complications, both in the transport binding and > with XML processing. > > * To imply a processing order by the arrangement of the modules. If > so, what significance does placing modules after the body have? It can be useful to have footers at the generation stage. To take the example of a checksum again, it is convenient for the XP sender to be able to include it after the body. The processing stage is trickier. > Is the assumption that XP messages will only be considered as a whole > well-founded? If so, perhaps this should be a requirement or > restriction of some kind. If not, we should discuss the implications > (I haven't fully thought them through, I just faintly hear alarm > bells ;). I didn't find a requirement about this. R701b[1] expresses the requirement to define a processing model, but doesn't go into that much detail. I remember a discussion about an XP processor starting to process a message (for example starting to send an XP message back with a response to an RPC) and then being forced to generate a fault, which makes me think that indeed XP messages have to be processed as a whole. On the other hand, R309[2] is about resource constrained device. As Noah pointed out[3], the issues related to resource constrained devices have not been discussed in detail; I could imagine a system with very limited memory wanting to process an XP message "on the fly". So I think that it is an open issue. But I agree that not considering XP messages as a whole will lead to complication, and that to keep the processing model simple, considering XP messages as a whole is a good idea. 1. http://www.w3.org/2000/xp/Group/xp-reqs-05#z701b 2. http://lists.w3.org/Archives/Public/xml-dist-app/2001Jan/0021.html 3. http://lists.w3.org/Archives/Public/xml-dist-app/2001Jan/0020.html -- Hugo Haas - W3C/MIT mailto:hugo@w3.org - http://www.w3.org/People/Hugo/ - tel:+1-617-452-2092
Received on Wednesday, 24 January 2001 10:33:56 UTC